What substances absorb moisture or promote the retention of moisture in hair care products?

Humectants are substances that have the ability to attract and retain moisture from the environment, making them essential ingredients in hair care products, especially for those aiming to hydrate and nourish the hair. These compounds work by drawing water molecules from the air into the hair shaft, helping to maintain optimal moisture levels and prevent dryness. This characteristic is particularly beneficial in products designed for curly or textured hair, as they often require additional hydration to maintain definition and manageability.

Emollients, on the other hand, primarily serve to soften and smooth the hair and skin by creating a barrier that prevents water loss. While they contribute to the overall hydration of the hair, their mechanism differs from that of humectants, which focus on actively drawing in moisture.

Surfactants are primarily used for cleansing and foaming functions in hair care products. They help to remove dirt and oil from the hair but do not have moisture-attracting properties.

Conditioners are formulated to improve the texture and appearance of hair, often incorporating emollients, humectants, and other ingredients. However, the specific role of humectants in retaining moisture is what directly addresses the question. Thus, humectants stand out as the key ingredient for moisture absorption in hair care formulations.